Halotolerant Bacillus Strains from Indonesian Sand Dunes Show Strong Biofertilizer Potential Under Salt Stress

Halotolerant Bacteria from Indonesian Sand Dunes Offer New Pathways Toward Sustainable Agriculture

A newly published study reveals that the Parangkusumo coastal sand dunes of Indonesia—an ecosystem marked by extreme salinity, heat, and nutrient-poor soils—harbor halotolerant bacteria with remarkable plant growth-promoting properties. Researchers isolated ten bacterial strains, most belonging to the genus Bacillus, from the rhizosphere and surrounding soils of the native halophyte Calotropis gigantea.

The study identified key functional traits among the isolates, including phosphate solubilization, nitrogen fixation, cellulose degradation, and anti-phytopathogenic activity. These properties are essential for supporting plant growth in harsh environments such as coastal agricultural zones.

Three isolates—Bacillus aryabhattai, B. subtilis, and B. subtilis subsp. spizizenii—were highlighted for their superior salt tolerance and consistent performance under both normal and high-salinity conditions. Importantly, antagonistic assays showed that these strains do not inhibit one another, indicating strong compatibility for the development of a multi-strain microbial consortium.

Consortium Dramatically Improves Sesame Growth Under Salt Stress

One of the most compelling findings came from germination experiments using sesame (Sesamum indicum) seeds. At 150 mM NaCl, seeds treated with the three-strain bacterial consortium exhibited significantly higher germination rates and greater biomass accumulation than individual-strain treatments and control seeds.

This synergistic effect suggests that combining compatible halotolerant PGPR may offer a more powerful biofertilizer solution for crops grown in saline or degraded soils.

Toward Practical Biofertilizer Applications

Because these isolates excelled in multiple PGPR functions—nutrient mobilization, stress tolerance, pathogen suppression, and compatibility—the study emphasizes their promise for real-world agricultural use. The authors note that future work should include field trials, crop-specific optimization, and development of scalable biofertilizer formulations tailored for coastal or salt-affected regions.

Reference

Geraldi, A., Salsabella, D.T., Tyautari, I. et al. Isolation and characterization of halotolerant bacteria from Indonesian sand dunes ecosystem and their plant growth-promoting properties. J. Saudi Soc. Agric. Sci. 24, 49 (2025). https://doi.org/10.1007/s44447-025-00055-2